The present invention relates to a packaging apparatus and, in particular, an apparatus for making filter paper bags containing infusable products such as tea, coffee or chamomile.
The use of filter paper bags, referred to more simply as tea bags, for making infusions has become widespread throughout the world because they are so handy and easy to use.
The increasing world-wide popularity of tea bags has led distributors of tea and other infusable products to invest huge resources into research targeted to improving tea bag design and ease of use.
This research has aimed to improve tea bag forms, the ease with which the product is released into the liquid during infusion, shelf life, ease of packaging the tea bags into their final containers and so on.
Over the years, the original single-lobed tea bag, with pick-up thread and tag has been replaced by the now well-established two-lobed tea bag (still with pick-up thread and tag and with or without individual overwrap). The two-lobed tea bag is made from a piece of tubular filter paper filled with two charges of infusable product each in a separate pouch. The two pouches are then folded over each other so that there is a larger surface area in contact with the liquid thus allowing the two charges of product inside the pouches to infuse more effectively.
A more recent market development has been the possibility of making tea bags which, after infusion, that is to say, at the moment they are removed from the liquid, can be squeezed in order to wring as much liquid as possible from the bag and also to prevent the liquid from dripping while the bag is being disposed of.
This squeeze feature allows the user to make the most of that part of the infusion (usually containing a high concentration of product) which is normally lost when the tea bag is removed from the pot and thrown away. The squeezing action is achieved by pulling the thread which typically attaches the tea bag to the tag. At present, the squeeze feature is applied to single-lobed tea bags, as disclosed, for example, by international patent publications N. WO-94/22721, or N-WO-95/10461 and WO-95/10462 or N. WO-96/15033 and WO-95/27666.
Attempts have recently been made to apply the squeeze feature to the two-lobed, and more widely-used, tea bags as well.
To obtain two-lobed tea bags of this kind, it is necessary to provide tea bags with squeezing means that are practical and reliable for users and, at the same time, economical enough not to raise the unit cost of each tea bag.
In this regard, we refer to the two-lobed tea bag described in patent application N. WO-97/19005 where, between the two pouches which contain the product charges and whose opposite ends are joined to each other, there is a thread by which the tea bag can be held during infusion and which is attached to a first area at the bottom end of the bag and not forming part of the product pouches. The thread extends to a second area at the top end of the tea bag and again in the space between the two folded pouches.
The thread is looped in such a way that it forms a coil between the two pouches that does not protrude from the sides of the tea bag itself. The thread loop is attached to the said end areas. The thread is also attached to a tag which allows the user to pull it and thus squeeze the tea bag.
The squeezing action is enhanced by the fact that between the pouches the coil forms a cross which makes it easier to draw the opposite corners of the tea bag together.